The present invention relates to filters having vertical filter elements, for example cartridge filters or candle-shaped filters as supports for a preliminary layer, which are used for the treatment of condensed water, particularly but not exclusively in the nuclear industry.
Known filters comprise a cylindrical housing having a vertical axis, which is closed at each end by a convex plate and in which a horizontal plate supporting a plurality of vertical cartridges or candles is disposed. These cartridges or candles are constituted by, for example, perforated hollow cylinders about which may be wound a sleeve of synthetic fiber which may receive a layer of material known as a preliminary layer for example ion exchange resin, diatomaceous earth, cellulose or active carbon, selected in terms of the water to be filtered. The water to be filtered is introduced at the base of the filter, penetrates inside the cartridges or candles and the treated water is collected by piping in the upper portion of the filter. Moreover, a vent is provided on the upper convex plate and provides an air drain.
These filters are used in the nuclear industry to treat radioactive water and are therefore disposed in a protective housing, generally of concrete, handling and dismounting of these filters being carried out at a distance through an orifice drilled in the protective housing. As the outlet piping for the air and the water in the upper part of the filter complicate such operations, access to the connection flanges is difficult.
In some filters the vertical filter elements are supported by a floor-plate disposed at the base of the filter above a water collection chamber for the treated water which is discharged at the lower portion of the filter. An air drain is, however, necessary in the upper portion of the filter. In addition, the dismounting of the filter elements requires the removal through the top, of the assembly in the housing above the floor-plate supporting the filter elements, which represents a considerable weight.
It is an object of this invention to provide a filter in an improved form.